Local Illumination Compensation in Video Coding

The patent applies LIC selectively only to boundary blocks of coding tree units (CTUs) rather than uniformly to all blocks. This local quality approach enables illumination compensation where it is most needed (at boundaries where illumination changes occur) while avoiding unnecessary processing in inner blocks, thus improving compression ratio for boundary regions without proportionally increasing overall encoding complexity.

The patent segments the video content by distinguishing between boundary blocks and inner blocks within CTUs. This segmentation allows different LIC processing strategies to be applied to different segments, with full LIC applied to boundary blocks and inheritance or simplified processing applied to inner blocks, thereby managing encoding complexity while maintaining compression effectiveness.

The patent performs preliminary action by deriving LIC parameters for boundary blocks first, then using these derived parameters as inheritance sources for inner blocks. This preliminary derivation at boundary locations allows inner blocks to reuse established parameters rather than performing independent derivations, reducing processing time while maintaining adaptability through the inheritance mechanism that allows parameter updates when conditions warrant.

The patent implements self-service through the parameter inheritance mechanism where inner blocks automatically acquire LIC parameters from adjacent boundary blocks without requiring independent parameter derivation. This self-service approach reduces processing time significantly, as inner blocks simply inherit and apply parameters from their neighbors rather than performing complex local derivations, while still maintaining adaptability when boundary conditions change.